Nickel electroplating baths



United States Patent 3,116,225 NECKEL ELECTR'SPILATENG EATHS Gregor Michael, Dusseldorf, and Wennemar Strauss,

Dusseldorf-Hoithauscn, Germany, assignors to Dehydag, Deutsche Hy-drierwerke Ganhll, Dusseldorf, German a corporation of Germany No Drawing. Filed July 3, 1961, Ser. No. 121,373 Claims priority, application Germany Italy 30, 1960 11 Claims. (Cl. 204-49) This invention relates to a method for producing bright nickel electrodeposits and nickel electroplating baths. It more particularly relates to additives for such processes and baths which make them resistant to impurities in the electroplating baths.

It is an object of this invention to provide a bright nickel electroplating process and bath which is not affected by impurities in the baths.

Another object is to provide a method and bath for obtaining bright nickel electrodeposits wherein filtration of the bath is substantially eliminated.

It is well known that full-bright nickel electro-plating baths are very sensitive toward impurities, such as hardness components of tap water, impurity components of technical grade nickel salts, electrode scum, dust particles and the like. In order to avoid bath turbidity, which is detrimental to the quality of the nickel electroplates, the baths must be continuously filtered; usually, from 1 to 2 bath volumes per hour must be pumped through the filter.

We have now found that nickel electroplating baths containing brightening agents and wetting agents can be made substantially resistant against impurities by the addition of condensation products of organic amides and oxo compounds, said condensation products containing sulfonic acid groups.

By adding the above mentioned condensation products, the nickel electrodbaths can be made so tolerant against bath impurities that the necessity of filtering is substantially reduced or that a continuous filtration can be completely eliminated.

The condensation products to be employed are known reaction products containing sulfonic acid groups which are obtained from organic diand poly-amides and oxo compounds, especially formaldehyde. These products may be used in conjunction with known nickel brightening agents, such as organic disulfimides, organic disulfonamides, dihalodiarlysulfonamides, mercaptoalkene sulfonic acid salts, haloalkane sulfonic acid salts and the like.

Examples of condensable diand poly-amides which are used to build the above mentioned sulfonic acids are the following: urea, thiourea, alkylureas, alkylthioureas, methyleneurea, ethyleneurea, guanidine, biuret, dicyandiamide, dicyandiamidine, alkyl guanidines, as well as cyclic compounds such as methyldiaminotriazine, melamine, melam, melern, mellone, ammeline and the like.

Examples of condensation components which may be used for the introduction of the sulfonic acid groups are alkyl sulfonic acids, cycloalkyl sulfonic acids, aryl sulfonic acids, alkyl-cycloalkyl sulfonic acids and alkyl-aryl sulfonic acids, as well as inorganic sulfites and bisulfites. Of particular importance among these are the aromatic sulfonic acids, such as benzene sulfonic acids, phenol sulfonic acids and naphthalene sulfonic acids as well as sulfonated condensation products of benzene, naphthalene or diphenyl with aldehydes, especially with formaldehyde. The sulfonic acid radicals may also be introduced by condensing sodium bisulfite into the condensation products.

Examples of suitable oxo compounds or substances yielding oxo compounds, which may be used for the preparation of the condensation products, are primarily formaldehyde, p-formaldehyde, tetrahydroxymethylene, hexamethylenetetramine, methylal, formaldehyde bisulfiite, acetaldehyde, crotonaldehyde, benzaldehyde, acetone, acetophenone, cyclohexanone and the like; among these, formaldehyde is again of particular practical importance.

The condensation products which make the electroplating baths resistant against bath impurities may essentially be used in combination with all nickel brightening agents. However, the process may be performed with particular advantage if the electroplating baths contain organic sulfocarbonimides as brightening agents. Such brightening agents are generally added in the quantities of 05-20 g./l. preferably between 2-5 g./l. Under these conditions, extraordinary brightening effects are obtained even if the bath is highly contaminated with impurities.

Among the group of sulfocarbonimides, which may be used in combination with the above mentioned condensaion products, the following compounds are especially effective: N-acetyltoluene sulfonamide, N-benzylbenzene sulfonarnide, N-acetyloctyl sulfonamide, N-toluylbutyl sulfonamide, N-lauroylbenzene sulfonamide, N-benzoylcyclohexyl sulfonamide, N,N' bis-(p-toluenesulfonyD- tartaric acid diamide, N,N-bis-(xylene-sulfonyl)-adipic acid diamide.

The condensation products are prepared in accordance with known methods by refluxing a mixture of the condensable dior poly-amides with the neutral salt of an organic sulfonic acid and the 0x0 compound from /2 to 3 hours at a temperature of 50 to 100 C. or by refluxing a mixture of the condensable dior poly-amides with sodium bisulfite and the oxo compound for several hours at the boiling point. The reactants for the condensation are used generally in the folloWing mol ratios-amide: organic sulfonic acid or bisulfite:oxo compound as 120.1:2-10, preferably 1:0.20.5:35. The condensation reaction mixture is then generally worked up by spray drying.

The amounts in which the condensation products according to the present invention are added to the electroplating baths are between about 0.0005 gm. and 4 gm. per liter, preferably between 0.02 and 0.1 gm. per liter, of bath fluid.

The composition and method of employment of the electroplating baths according to the present invention are further illustrated by the following examples. The baths may also contain customary wetting agents, as well known in the art, such as high molecular alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates or ethoxylation products of high molecular compounds, which contain exchangeable hydrogen atoms.

The following specific examples are set forth to further illustrate the invention and to enable persons skilled in the art to better understand and practice the invention, and are not intended to be limitative.

Example I When a Watts-type nickel bath, which contains as a brightening agent 2.5 g./l. N-acetyltoluene sulfonamide and as a wetting agent 0.2 g./l. of sodium dodecylsulfate, is modified with 0.03 g./l. of the condensation product of dicyandiamide, melamine, dinaphthylmethylene disodium sulfonate and formaldehyde, which has been obtained by refluxing the components in a molar ratio of dicyandiamide:melamine:dinaphthylmethane disodium sulfonatezformaldehyde as 1:1:0.5:9 at C. for /2 hour, a bath is obtained which produces full bright, level nickel electroplates at 5060 C. in a current density range of 0.1 to 8 amp./dm. The bath can be operated completely without filtration and no pore or scale formation occurs on the nickel electroplates even over long periods of use.

Example II When a W atts-type nickel bath as described in Example I is modified with 0.025 g./l. of the condensation product of dicyandiamide, naphthalene sodium sulfonate and formaldehyde, which has been obtained by refluxing the components in a molar ratio of dicyandiamide:naphthalene sodium sulfonatezformaldehyde as l:0.4:3.75 at 85 C. for 20 minutes, full bright, level nickel electroplates are obtained at 50 to 60 C. in a current density range of 0.1 to 8 amp/dm. and the bath exhibits the same excellent stability properties against bath impurities as that described in Example I.

Example III When a Watts-type nickel bath as described in Example I is modified with 0.04 gm./l. of the condensation product of dicyandiamide, guanidine hydrochloride, sodium bisulfite and formaldehyde as the stabilizing agent against bath impurities, the condensation product having been obtained by refluxing 1 mol of dicyandiamide, 1 mol of guanidine hydrochloride, 1 mol of sodium bisulfite and 9 mols of formaldehyde at the boiling point for hours, the same results are obtained as in Examples I and II with respect to brightness and resistance against bath impurities.

Example IV 1 When a Watts-type nickel bath as described in Example I is modified with 0.06 gm./l. of the condensation product of dicyandiamide, sodium bisulfite and formaldehyde, the condensation product having been obtained by refluxing 1 mol of dicyandiamide, 1 mol of guanidine hydrochloride, 1 mol of sodium bisulfite and 9 mols of formaldehyde at the boiling point for 5 hours, a bath is obtained which is resilient against impurities and which produces full bright, level nickel electroplates over long period of use without requiring filtration.

Example V When a Watts-type nickel bath as described in Example I is modified for the purpose of stabilization against impurities with 0.03 g./l. of the condensation product of ethyleneurea, dinaphthylmethane disodium sulfonate and formaldehyde, the condensation product having been obtained by refluxing the components in a molar ratio of ethyleneurea dinaphthylmcthane disodium sulfonate: formaldehyde as 1:0.23 :3.75 for 20 minutes at 85 C., this bath always produces full bright, level nickel electroplates which exhibit no signs of pores or scale formation, even during continuous operation without filtration.

Example VI When a Watts-type nickel bath as described in Example I is modified for the purpose of stabilization of the bath against impurities with 0.04 gm./l. of the condensation product of dicyandiamide, formaldehyde, sodium bisulfite and urea, the condensation product having been obtained by refluxing 0.5 mol dicyandiamide, 0.5 mol urea, 0.8 mol sodium bisulfite and 3.5 mols formaldehyde at the boiling point for 4 hours, full bright nickel electroplates are obtained upon electroplating all iron and copper surt aces. The bright nickel deposit is not affected by bath impurities.

Example VII When the condensation product used in Example VI was replaced by the condensation product of dicyandiamide, dinaphthylmethane sodium sulfonate, formaldehyde and acrolein, obtained by refluxing the components in a molar ratio of dicyandiamide:dinaphthylmethane sodium sulfonatezformaldehyde:acrolein as 1:0.5:2:75:1 for 1 hour at 80 C., the addition of 0.02 gm./l. of this condensation product also produces full bright nickel electroplates with the nickel bath according to Example I, the electroplates being also unaffected with respect to i brightness and smoothness by bath impurities and turbidities.

Example VIII When [a Watts-type nickel bath as described in Example I is modified with 0.05 gm./l. of the condensation product of dicyandiamide, dinaphthylmethane sodium sulfonate, formaldehyde and formamide, obtained by refluxing the components in a molar ratio of dicyandiamidezformamide:dinaphthylmethane sodium sulfonatezformaldehyde as l:l:0.6:6 for /2 hour at C., full bright level nickel electroplates are obtained which are free from scales and pores.

Example IX Very good brightening eifects are also obtained when a Watts-type nickel bath as described in Example I is modified with 0.02 gm./l. of the condensation product of dicyandiamide, dinaphthylmethane sodium sulfonate, formaldehyde and amino-sulfonic acid, obtained by refluxing the components in a molar ratio of dicyandiamide: amino-sulfonic acid:dinaphthylmethane sodium sulfonate:for-maldehyde as 1.5:0.5:0.4:6 for /2 hour at 85 C. Bath impurities and turbidities do not interfere.

Example X Very good nickel electroplates are also obtained when a Watts-type nickel bath as described in Example I is modified for the purpose of stabilizing the bath against i-mpurities with 0.035 gin/l. of the condensation product of dicyandiamide, idinaphthylmethane sodium sulfonate, formaldehyde and propionic acid amide, obtained by refluxing the components in a molar ratio of dicyandiarnidezpropionic acid amidezdinaphthyl-methane sodium sulfonatezformaldehyde as 1:1:0.8:6 for /2 hour at 85 C. In the presence of colloidal substances which cause bath turbidity, these nickel electroplates are also full bright and free from pores and scales.

While we have set forth certain specific embodiments and preferred modes of practice of our invention it Will be understood that these were solely for the purpose of illustration, and that various changes and modifications may be made in the invention without departing from the spirit of the disclosure and the scope of the appended claims.

We claim:

1. A process for producing bright nickel electrodeposits from Watts-type nickel plating baths containing a brightening agent, which comprises adding to said bath a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (a) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oxo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of 1:01-1:2-10 at temperatures from about 50 to C. for a time from about 20 minutes to 5 hours, whereby said process is unaffected by impurities in said bath.

2. A process for producing bright nickel electrodeposits from Watts-type nickel plating baths containing a brightening agent, which comprises adding to said bath from about 0.0005 to about 4 g./l. of bath of a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (:1) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oxo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of l:0.l1:2l0 at temperatures from about 50 to 100 C. for a time from about 20 minutes to 5 hours, whereby said process is unaffected by impurities in said bath.

3. A process for producing bright nickel electrodeposits from Watts-type nickel plating baths containing a brightening agent, which comprises adding to said bath from about 0.02 to about 0.1 g./l. of bath of a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (a) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oxo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of 1:0.21:26 at temperatures from about 5-0 to 100 C. for a time from about 20 minutes to 5 hours, whereby said process is unaffected by impurities in said bath.

4. A process for producing bright nickel electrodeposits from Watts-type nickel plating baths containing an organic sulfocarbonimide as a brightening agent, which comprises adding to said bath a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (a) organic amides, (b) sulfa-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oXo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of l:0.11:2-l0 at temperatures from about 50 to 100 C. for a time from about 20 minutes to 5 hours, whereby said process is unaffected by impurities in said bath.

5. A process for producing bright nickel electrodeposits from Watts-type nickel plating baths containing a brightening agent, and a wetting agent, which comprises adding to said bath a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (a) organic amides, (b) sultocompounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and 0X0- compounds selected from the group consisting of aldehydes and ketones in a molar ratio of 1:0.11:2-10 at temperatures from about 50 to 100 C. for a time from about 20 minutes to 5 hours, whereby said process is unaifected by impurities in said bath.

6. A Watts-type nickel electroplating bath for obtaining bright electrodeposits stabilized against impurities in said bath comprising a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (a) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oxo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of 1:0.1-122-10 at temperatures from about 50 to 100 C. for a time from about 20 minutes to 5 hours.

7. A Watts-type bright nickel electroplating bath for obtaining bright nickel electrodeposits stabilized against impurities in said bath comprising a brightening agent and a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (an) organic amides (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) 0210- compounds selected from the group consisting of aldehydes and ketones in a molar ratio of 1:0.1-1:2-10 at temperatures from about 50 to 100 C. for a time from about 20 minutes to 5 hours.

8. A Watts-type bright nickel electroplating bath 'for obtaining bright nickel electrodeposits stabilized against impurities in said bath comprising a brightening agent and from about 0.0005 to about 4 g./l. of bath of a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating ((1.) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oxo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of l:0.1l:210 at temperatures from about 50 to C. for a time from about 20 minutes to 5 hours.

9. A Watts-type bright nickel electroplating bath for obtaining bright nickel electrodeposits stabilized against impurities in said bath comprising a brightening agent and from about 0.02 to 0.1 g./l. of bath of a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating ((1) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) 0Xo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of l:0.2-1:26 at temperatures from about 50 to 100 C. for a time from about 20 minutes to 5 hours.

10. A Watts-type bright nickel electroplating bath for obtaining bright nickel electrodeposits unaffected by impurities in said bath comprising an organic s-ulfocarbonimide as a brightening agent and a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction product by heating (tr) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oxo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of 1:0.1-1:210 at temperatures from about 50 to 100 C. *for a time from about 20 minutes to 5 hours.

11. A Watts-type bright nickel electroplating bath for obtaining bright nickel electrodeposits unaffected by impurities in said bath comprising a brightening agent, a Wetting agent and a compound containing free sulfonic acid groups, said compound resulting from a condensation reaction produced by heating (a) organic amides, (b) sulfo-compounds selected from the group consisting of organic sulfonic acids and salts of sulfurous acid, and (c) oXo-compounds selected from the group consisting of aldehydes and ketones in a molar ratio of 1:0.1-122-10 at temperatures from about 50 to 100 C. for a time from about 20 minutes to 5 hours.

References Cited in the file of this patent UNITED STATES PATENTS 2,757,133 Shenk July 31, 1956 2,795,540 Brown June 11, 1957 2,828,252 Fischer Mar. 25, 1958 2,870,069 Ostrow et al Jan. 20, 1959 

1. A PROCESS FOR PRODUCING BRIGHT NICKEL ELECTRODEPOSITS FROM WATTS-TYPE NICKEL PLATING BATHS CONTAINING A BRIGHTENING AGENT, WHICH COMPRISES ADDING TO SAID BATH A COMPOUND CONTAINING FREE SULFONIC ACID GROUPS, SAID COMPOUND RESULTING FROM A CONDENSATION REACTION PRODUCED BY HEATING (A) ORGANIC AMIDES, (B) SULFO-COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF ORGANIC SULFONIC ACIDS AND SALTS OF SULFUROUS ACID, AND (C) OXO-COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF ALDEHYDES AND KETONES IN A MOLAR RATIO OF 1:0.1-1:2-10 AT TEMPERATURES FROM ABOUT 50 TO 100*C. FOR A TIME FROM ABOUT 20 MINUTES TO 5 HOURS WHEREBY SAID PROCESS IS UNAFFECTED BY IMPURITIES IN SAID BATH. 